Nakanishi hypothesized that a cascade reaction of these functional groups might generated certain ladder compounds found in red tides. The Payne rearrangement leads to the isomerization of this functional group. The reaction of trimethylsulfonium iodide, base, and a ketone yields this functional group in one reaction, though that reaction can also create the similar aziridine group when a nitrogen containing compound is used. A more canonical synthesis makes use a concerted intermediate step resembling a (*) butterfly and uses an olefin and peracid as reactants--that synthesis is sometimes named for Prilezhaev. This functional group can be "opened" by nucleophiles to relieve ring strain and 
Nakanishi hypothesized that a cascade reaction of these functional groups might generated certain ladder compounds found in red tides. The Payne rearrangement leads to the isomerization of this functional group. The reaction of trimethylsulfonium iodide, base, and a ketone yields this functional group in one reaction, though that reaction can also create the similar aziridine group when a nitrogen containing compound is used. A more canonical synthesis makes use a concerted intermediate step resembling a (*) butterfly and uses an olefin and peracid as reactants--that synthesis is sometimes named for Prilezhaev. This functional group can be "opened" by nucleophiles to relieve ring strain and yields an alcohol. FTP, name this functional group similar to a cyclic ether which consists of a three-membered ring containing an oxygen atom.
Nakanishi hypothesized that a cascade reaction of these functional groups might generated certain ladder compounds found in red tides.
{epoxide} [accept {oxirane}]